import numpy as np
import pandas as pd
arr= np.random.randint(1,20,size=(3,3))
df=pd.DataFrame(arr,columns=['c','b','a'])
print("原始数据:\n",df)
print("按行索引降序排序:\n",df.sort_index(ascending=False))
print("按列索引降序排序:\n",df.sort_index(axis=1))